The development of commercially acceptable coated plastic films for printing applications, e.g., printable labels, is often a compromise between a variety of desired properties. One such requirement for coated plastic films is wet-scratch resistance, which is a primary concern in label applications. Other properties that coated plastic films for printing applications should provide are good graphics, ink gloss and short "tack up" times.
Unfortunately, coated plastic films that offer excellent print gloss, graphics and "tack up" times, normally exhibit poor wet-scratch resistance. Examples of commercially available plastic films that fall into this category are plastic films coated with acrylic polymers containing inorganic filler materials such as clay or talc (hereinafter "filled acrylic"). Moreover, such filled acrylic coatings are not clear. As a result, there are no clear coated lithographic films with excellent wet-scratch resistance available for use as printable labels.
The problem of wet-scratch resistance with the filled acrylic coated plastic films occurs when the coated film becomes exposed to water for more than five minutes. This frequently occurs when the plastic films are used as labels in bottling operations, in which the labels are applied to the bottles before filling and washing. The bottles, once filled and washed, are packaged and shipped within close proximity of each other and the packaging material. During shipment jostling of the packages occurs, which causes severe abrasion of the printed ink images on the labels. The abrasion eventually results in the ink being removed from the label and causing the final product to lose shelf appeal.
Attempts to counter the deficiency of filled acrylic coated films have resulted in other film structures being developed. Although these alternative printable films exhibit excellent wet-scratch resistance, they do so at the detriment of image graphics, ink gloss and tack up times as compared with the filled acrylic coated plastic films.
Thus, there is a need in the art for printable coated plastic films that exhibit wet-scratch resistance while at the same time providing the ink gloss, graphics and tack up times of the filled acrylic coated plastic films currently available in the market. Moreover, there is a need in the art for clear coated plastic labels having excellent wet-scratch resistance for printing applications, which presently are not commercially available.
Accordingly, it is an object of the present invention to provide printable coated plastic films that exhibit wet-scratch resistance while at the same time providing the ink gloss, graphics and tack up times comparable to filled acrylic coated plastic films. It is also an object of the present invention to clear coated plastic labels having excellent wet-scratch resistance for printing applications.